2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34" Prepared by Dynamic Engineering Printed 2/10/2026 HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 83
Summary for Pond 21P: Basin A Routing (StormBrixx)
Inflow Area = 0.740 ac, 97.30% Impervious, Inflow Depth = 5.95" for 10-Year-Projected event
Inflow = 2.86 cfs @ 12.19 hrs, Volume= 0.367 af
Outflow = 0.70 cfs @ 12.86 hrs, Volume= 0.367 af, Atten= 75%, Lag= 40.0 min
Discarded = 0.70 cfs @ 12.86 hrs, Volume= 0.367 af
Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routed to Link 14L : Study Area West (Total)
Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
Peak Elev= 118.68' @ 12.86 hrs Surf.Area= 3,001 sf Storage= 3,445 cf
Plug-Flow detention time= 26.6 min calculated for 0.367 af (100% of inflow)
Center-of-Mass det. time= 26.6 min ( 782.3 - 755.7 )
VolumeInvertAvail.StorageStorage Description
#1A117.50'0 cf31.63'W x 94.88'L x 3.00'H Field A
#2A117.50'8,729 cf8,999 cf Overall - 8,999 cf Embedded = 0 cf x 40.0% Voids ACO StormBrixx SD 1 x 384 Inside #1 Inside = 23.7"W x 36.0"H => 5.75 sf x 3.95'L = 22.7 cf Outside = 23.7"W x 36.0"H => 5.93 sf x 3.95'L = 23.4 cf 384 Chambers in 16 Rows
8,729 cf Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Primary117.50'15.0" Round Culvert L= 22.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 117.50'/ 117.40' S= 0.0045'/' Cc= 0.900 n= 0.013, Flow Area= 1.23 sf
#2Device 1118.81'6.0" Vert. Orifice C= 0.600 Limited to weir flow at low heads
#3Discarded117.50'10.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = -4.00'
Discarded OutFlow Max=0.70 cfs @ 12.86 hrs HW=118.68' (Free Discharge)\n uparrow3=Exfiltration ( Controls 0.70 cfs)
Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=117.50' (Free Discharge)\n uparrow1=Culvert ( Controls 0.00 cfs)\n uparrow2=Orifice ( Controls 0.00 cfs)
2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34" Prepared by Dynamic Engineering Printed 2/10/2026 HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 84
Pond 21P: Basin A Routing (StormBrixx) - Chamber Wizard Field A
Chamber Model = ACO StormBrixx SD 1 (ACO StormBrix Inside = 23.7"W x 36.0"H => 5.75 sf x 3.95'L = 22.7 cf Outside = 23.7"W x 36.0"H => 5.93 sf x 3.95'L = 23.4 cf 24 Chambers/Row x 3.95' Long = 94.88' Row Length 16 Rows x 23.7" Wide = 31.63' Base Width 36.0" Chamber Height = 3.00' Field Height 384 Chambers x 22.7 cf = 8,728.7 cf Chamber Storage 384 Chambers x 23.4 cf = 8,998.6 cf Displacement Chamber Storage = 8,728.7 cf = 0.200 af Overall Storage Efficiency = 97.0% Overall System Size = 94.88' x 31.63' x 3.00' 384 Chambers 333.3 cy Field
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